Black inks based on biochar

ABSTRACT

The present invention provides a water-based black ink, utilizing biochar as the black pigment. The black inks of the invention contain high bio-renewable carbon content (BRC), preferably 100% BRC. The inks exhibit the physical properties required to perform according to the requirements of rotogravure and flexographic printing.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 63/221,153, filed 13-July-2021, which is hereby incorporated in itsentirety.

FIELD OF THE INVENTION

The present invention is related to black inks and coatings containinghigh bio-renewable carbon. The inks and coatings contain water,pyrolyzed cellulose (e.g. biochar) pigment, and a rosin adduct. The inksand coatings of the present invention are microwave safe.

BACKGROUND OF THE INVENTION

The printing ink industry has been attempting to construct productsusing a maximum quantity of renewable and responsibly sourced carbon forseveral years. Limitations in raw materials include the percentage ofsustainably sourced carbon, and the requisite chemistries to provideacceptable physical performance.

There are two general forms of carbon materials in printing inks. Thefirst form of carbon materials represent high BRC (bio-renewablecontent) materials, i.e. those with carbon originating from recentlyliving sources (naturally derived materials). The second type are rawmaterials originating from ancient carbon (e.g. petroleum, coal), whichare considered low or zero BRC. The responsible ink formulation trend isto replace low BRC materials with higher BRC materials to diminish theenvironmental and climatic impact of the final degradation product –carbon dioxide. Within the ink industry, one method for BRCdetermination, as a percentage of the total carbon in a material, ismeasuring the ratio of carbon 14 isotope (14C) to carbon 12 isotope(12C) present in the sample, and comparing to a known reference. Carbon14 testing is widely referred to as “carbon dating,” which determinesthe age of a sample by counting the beta radiation emitted per microgramof carbon content. With consideration of a 5730 year half-life for 14C,any samples known to contain raw materials less than 300 years sincelast alive, counting beta emissions can also determine the relativepercentage of sustainable (BRC) carbon and the percent of ancientcarbon. There are some challenges in the BRC method, including the timeperiod from 1950 to 2015. From 1950 to 1963 above-ground nucleardetonations elevated the 14C content in the earth’s atmosphere as CO2,by as much as 190%. The amount of 14C peaked in 1963, and the plants onearth have been consuming that excess 14C since, reverting 14C back tothe pre-1950 levels in 2015. Those years are also part of the historicreference for BRC comparison. If the age (since living) of the testsample is known, BRC can accurately be normalized for materials living1950 through 2015.

WO 2021/062312 discloses plant char carbon pigments, which may beprovided as liquid dispersions. The plant char carbon pigments areproduced by pyrolyzing carbohydrates (i.e. plant material). The pigmentdispersions may comprise microfibrillated cellulose, which is includedin the milling fluid. Microfibrillated cellulose is a particulate formof cellulose that is a polysaccharide that can function as ananticoagulant by intercalating in between pigment particles, but it isnot soluble in water.

WO 2021/231829 describes inks and coatings having high BRC that compriserosin adducts. There is no disclosure of biochar used as pigments.

BRIEF SUMMARY OF THE INVENTION

The present invention provides black ink and coating compositionscontaining 70% to 100% BRC, relative to the total carbon in thecomposition. The present invention is the first time that it has beenshown that pyrolyzed carbohydrates (e.g. biochar) can be used in afinished ink or coating, wherein the ink or coating has the necessaryphysical properties to satisfy the requirements in the printingindustry.

The black inks and coating compositions of the present inventioncomprise water, biochar pigment, and a rosin adduct, wherein the rosinadduct has 100% bio-renewable carbon (BRC) content.

In a particular aspect, the present invention provides a water-basedliquid black ink composition, comprising:

-   (a) 30 wt% to 50 wt% mixing vehicle, based on the total weight of    the ink composition, wherein the mixing vehicle comprises:    -   i. 10 wt% to 30 wt% water, based on the total weight of the        mixing vehicle;    -   ii. 5 wt% to 15 wt% of an L-lactic acid mixture, based on the        total weight of the mixing vehicle, wherein the L-lactic acid        mixture comprises 88 wt% L-lactic acid and 22 wt% water, based        on the total weight of the L-lactic acid mixture;    -   iii. 10 wt% to 30 wt% rosin adduct, based on the total weight of        the mixing vehicle;    -   iv. 10 wt% to 30 wt% of 14.5 Baume ammonia, based on the total        weight of the mixing vehicle;    -   v. 1 wt% to 10 wt% wax suspension, based on the total weight of        the mixing vehicle, wherein the wax suspension comprises 25 wt%        wax and 75 wt% water, based on the total weight of the wax        suspension;    -   vi. 1 wt% to 5 wt% micronized wax, based on the total of the        mixing vehicle;    -   vii. 0.05 wt% to 1 wt% silicone compound, based on the total        weight of the mixing vehicle; and    -   viii. 0.5 wt% to 3 wt% zinc chelating agent, based on the total        weight of the mixing vehicle; and-   (b) 50 wt% to 70 wt% black dispersion, based on the total weight of    the ink composition, wherein the black dispersion comprises:    -   i. 10 wt% to 40 wt% biochar, based on the total weight of the        black dispersion;    -   ii. 1 wt% to 5 wt% surfactant, based on the total weight of the        black dispersion;    -   iii. 5 wt% to 20 wt% of the mixing vehicle of part (a), based on        the total weight of the black dispersion; and    -   iv. 10 wt% to 50 wt% water, based on the total weight of the        black dispersion; wherein 75% to 100% of the carbon content in        the ink composition is bio-renewable carbon (BRC).

In some embodiments, the rosin adduct is a 100% BRC rosin ester resin,preferably a rosin-citrate ester resin.

In some embodiments, the ink and coating compositions of the presentinvention comprise 100% BRC.

These and other objects, advantages, and features of the invention willbecome apparent to those persons skilled in the art upon reading thedetails of the formulations and methods as more fully described below.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is the first disclosure of 100% BRC carboncontaining pigment materials (e.g. biochar) being used to produce afully functional printing ink when used in combination with 100% BRC inkresins and 100% BRC ink additives. The solution provided by the presentinvention is a combination of biochar and a 100% BRC rosin adduct, whichexhibits a comprehensive set of ink performance properties, as describedbelow.

It is to be understood that the foregoing general description and thefollowing detailed description are exemplary and explanatory only, andare not restrictive of any subject matter claimed.

Headings are used solely for organizational purposes, and are notintended to limit the invention in any way.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of skill in theart to which the inventions belong. All patents, patent applications,published applications and publications, websites and other publishedmaterials referred to throughout the entire disclosure herein, unlessnoted otherwise, are incorporated by reference in their entirety for anypurpose. Although any methods and materials similar or equivalent tothose described herein can be used in the practice or testing of thepresent invention, the preferred methods are described.

Definitions

In this application, the use of the singular includes the plural unlessspecifically stated otherwise. As used herein, the singular forms “a,”“an” and “the” are intended to include the plural forms as well, unlessthe context clearly indicates otherwise.

In this application, the use of “or” means “and/or” unless statedotherwise. Also, when it is clear from the context in which it is used,“and” may be interpreted as “or,” such as in a list of alternativeswhere it is not possible for all to be true or present at once.

As used herein, the terms “comprises” and/or “comprising” specify thepresence of the stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. Furthermore, to the extent that theterms “includes,” “having,” “has,” “with,” “composed,” “comprised” orvariants thereof are used in either the detailed description or theclaims, such terms are intended to be inclusive in a manner similar tothe term “comprising.”

When the terms “consist of”, “consists of” or “consisting of” is used inthe body of a claim, the claim term set off with “consist of”, “consistsof” and/or “consisting of” is limited to the elements recitedimmediately following “consist of”, “consists of” and/or “consistingof”, and is closed to unrecited elements related to that particularclaim term. The term ‘combinations thereof’, when included in thelisting of the recited elements that follow “consist of”, “consists of”and/or “consisting of” means a combination of only two or more of theelements recited.

As used herein, ranges and amounts can be expressed as “about” aparticular value or range. “About” is intended to also include the exactamount. Hence “about 5 percent” means “about 5 percent” and also “5percent.” “About” means within typical experimental error for theapplication or purpose intended.

It is to be understood that wherein a numerical range is recited, itincludes the end points, all values within that range, and all narrowerranges within that range, whether specifically recited or not.

Throughout this disclosure, all parts and percentages are by weight (wt%or mass% based on the total weight) and all temperatures are in °Cunless otherwise indicated.

As used herein, “natural material(s)” are materials that are botanic(plant-based), mineral-based, of animal original, derived frommicroorganisms, their reaction products, and combinations thereof, andwater. Natural materials may be used as they occur in nature, or theycan undergo processing that does not significantly alter the originalphysical, chemical, or biological state of the ingredient. Examples ofpermissible processing include dehydration, extraction, extrusion,centrifugation, filtration, distillation, grinding, sieving,compression, freezing, drying, milling, etc. Natural materials include,but are not limited to, water, natural resins, natural defoamers,natural waxes, natural colorants, bio-solvents, natural minerals, andthe like.

As used herein, “BRC” refers to bio-renewable carbon, which can furtherbe defined as non-ancient carbon (i.e. non-fossil-based carbon) that ispart of earth’s natural environment. Non-ancient carbon (less than40,000 years after final atmospheric carbon incorporation) containsradiocarbon (¹⁴C), whereas ancient (fossil-based) carbon does notcontain radiocarbon. BRC refers to naturally occurring renewableresources that can be replenished to replace the portion depleted byusage and consumption, either through natural reproduction, or otherrecurring processes in a finite amount of time (such as within a humanlifetime).

As used herein, “plant-based” refers to materials that contain equal toor greater than 50% of the ingredient mass from plant-based sources.

As used herein, “naturally derived” refers to materials with equal to orgreater than 50% natural or biobased origin by molecular weight, basedon renewable carbon content.

As used herein, “natural minerals” refers to inorganic materialsoccurring naturally in the earth, having a distinctive chemical formulaand consistent set of physical properties (e.g. crystalline structure,hardness, colors, etc.). Also included are “derived minerals” -materials obtained through chemical processing of inorganic substancesoccurring naturally in the earth, which have the same chemicalcomposition as natural mineral ingredients (e.g. calcium carbonate,silica, hydrated silica, sodium fluoride, titanium dioxide).

As used herein, “bio-based” refers to materials containing carbon ofrenewable origin from agricultural, plant, animal, fungi,microorganisms, marine, or forestry materials.

As used herein, “pyrolyzed carbohydrate(s),” “pyrolyzed cellulose,” and“biochar” refer to a carbonaceous material obtained by the partialcombustion or pyrolysis of vegetable and fruit wastes, bone, horn,ivory, and similar materials. Pyrolysis involves placing the material ina [0031] chamber and heating it in the presence of little or no oxygen.

As used herein, “renewable” refers to materials that are part of earth’snatural environment. Renewable resources are naturally occurring, andcan be replenished to replace the portion depleted by usage andconsumption, either through natural reproduction or other recurringprocesses, in a finite amount of time (such as within a human lifetime).

As used herein, “mixing vehicle,” “varnish,” and “grind varnish” referto a composition of the invention that does not contain pigment. Amixing vehicle, varnish, or grind varnish may be mixed with pigment andused as a colored ink or coating, or it may be used as is (i.e. nopigment) as a clear coating.

As used herein, “sustainable” refers to the quality of not being harmfulto the environment or depleting natural resources, and therebysupporting long-term ecological balance.

As used herein, “substrate” means any surface or object to which an inkor coating can be applied. Substrates include, but are not limited to,cellulose-based substrates, paper, paperboard, fabric (e.g. cotton),leather, textiles, felt, concrete, masonry, stone, plastic, plastic orpolymer film, spunbond non-woven fabrics (e.g. consisting ofpolypropylene, polyester, and the like) glass, ceramic, metal, wood,composites, combinations thereof, and the like. Substrates may have oneor more layers of metals or metal oxides, or other inorganic materials.Particularly preferred are non-woven substrates.

As used herein, the term “article” or “articles” means a substrate orproduct of manufacture. Examples of articles include, but are notlimited to: substrates such as cellulose-based substrates, paper,paperboard, plastic, plastic or polymer film, glass, ceramic, metal,composites, and the like; and products of manufacture such aspublications (e.g. brochures), labels, and packaging materials (e.g.cardboard sheet or corrugated board), containers (e.g. bottles, cans), apolyolefin (e.g. polyethylene or polypropylene), a polyester (e.g.polyethylene terephthalate), a metalized foil (e.g. laminated aluminumfoil), metalized polyester, a metal container, and the like.

As used herein, “inks and coatings,” “inks,” and “coatings” are usedinterchangeably, and refer to compositions of the invention, or, whenspecified, compositions found in the prior art (comparative). Inks andcoatings typically contain resins, solvent, and, optionally, colorants.Coatings are often thought of as being colorless or clear, while inkstypically include a colorant.

As used herein, the “face” of a printed or coated substrate refers tothe side on which the ink or coating has been applied.

As used herein, the “back” of a printed or coated substrate refers tothe side to which no ink or coating has been applied.

As used herein, an “unsaturated compound” is a carbon containingmaterial that contains one or more C=C bonds (carbon-carbon doublebonds).

Water-Based Compositions

The present invention uses 100% bio-renewable carbon components toprovide water-based black liquid inks with the requisite physicalproperties to perform within rotogravure and flexographic printingrequirements. The unique construction and interplay of materials is thekey feature that leads to a fully functional ink product. Although WO2021/162312 suggests that biochar can be used to pigment finished inks,only pigment dispersions, and not finished inks, are described.Furthermore, WO 2021/162312 does not disclose use of rosin resin adductsin combination with the biochar. The microfibrillated cellulose used inWO 2021/162312 s a particulate form of cellulose that is apolysaccharide that can function as an anticoagulant by intercalating inbetween pigment particles. It is not soluble in water and will not havethe function of a dispersant. Rosin resins used by the present inventionare terpene chemicals derived from natural rosins, modified to functionas dispersants by adsorbing onto the pigment particles and providing thesteric and ionic interactions to prevent the particles fromagglomerating. One of ordinary skill in the art would recognize thatmicrofibrillated cellulose and the rosin resin adducts of the presentare not equivalent, and cannot be used interchangeably.

Printing inks (and coatings) are a composite of multiple raw materials,each responsible for part of the overall performance, and all must becompatible with each other, insuring chemical stability over time. Aperson familiar with the art recognizes that a water-based printing inktypically contains about 30-40% carbon containing compounds, equal to orgreater than 60% water, and about 1% ammonia. Carbon contributionconsiders both the amount of carbon containing compounds in aformulation, and the amount of elemental carbon in each individualcompound. Representative carbon containing compounds are summarized forrelative elemental carbon contribution in Table A.

TABLE A Carbon contribution of compounds in a water-based ink TypicalComponents of a Water-Based Ink Typical Component amount used in aFinished ink Typical Mass% of Elemental Carbon found in componentRelative Elemental carbon Contribution Organic Pigment 16% 70% 47.4%Emulsion Resins 12% 60% 30.4% Solution Resins 5% 60% 12.7% Waxes andModifying Additives 3% 75% 9.5% Water and Ammonia 64% 0% 0%

The ink and coating compositions of the present invention preferablyhave a 100% BRC contribution for all elemental carbon containingcompounds. That is, it is preferred that no elemental carbon within anycomponent of the invention is less than 100% BRC. Pigment content hasbeen the major challenge to a 100% BRC ink, due to lack of sustainablecarbon (dye) intermediates, generally sourced from China, used tomanufacture organic pigments. Considering that organic colorantscontribute nearly half of the carbon content of a typical liquid ink,this fact would appear to be severely restricting to the construction ofa 100% BRC finished ink. Many carbon black pigment and pigmentdispersion commercial products containing sustainable carbon content donot attain 100% BRC. One carbon black example of partial sustainablecontent, yet non-attainment of 100% BRC, is Printex Nature Black byOrion. This lamp process pigment uses incomplete combustion of 100% BRCsoy bran waxes to produce a high BRC black pigment, yet the BRC islisted in the literature as 85%. Upon further inspection, natural gas(of ancient origin) is used to augment the combustion process,contributing non-sustainable carbon to the final pigment product.

Microwave susceptibility is known as a benefit for heating foods, yet itis a liability for printed inks. Printed inks (specifically many carbonblacks) often show the production of heat, smoke, sparks, and flameswhen exposed to microwave energy. Few high purity carbon pigment ancientsources (e.g. petroleum based) are microwave safe, due to very highcarbon content. Carbon pigments where oxygen content exceeds 4% tend tobe microwave safe, due to the non-susceptor property of oxygen. Biocharpigments derived from recently living organisms typically containgreater than 4% oxygen content (from residual lignin and cellulosestructures), and are typically microwave safe.

Compostability is a feature of chemical decomposition via heat, light,chemical reaction, and microbe metabolic activity. While not being boundby theory, the consensus is that components of ink that are closer to aliving natural structure tend to be more easily metabolized by microbesthan highly chemically modified compounds no longer similar to naturalfoodstuff structures.

There are special formulary considerations for biochar versus ancientsource carbon black pigment in a finished ink. Those considerationsinclude rheology and viscosity stability; applied density (pigmentdelivery at the desired viscosity); solids at the desired viscosity; andthe flexographic and rotogravure delivery to the substrate. All of theseperformance considerations are based upon cohesion and adhesioninteractions between components in the ink. The major differencesbetween biochar carbon and ancient source carbon are the amount ofoxygen content (propensity to form hydrogen bonding interactions), andthe structural resistance to mechanical disintegration.

Within a finished ink there are attractive hydrogen bonding interactionsbetween resin and pigment. Someone skilled in the art would describe afunctional amount of hydrogen bonding chemistries as required on boththe resin and pigment. Too little hydrogen bonding would not produce theadhesion and cohesion required for wet delivery from anilox to plate tosubstrate. On the other hand, if both resin and pigment containexcessive hydrogen bonding structures with geometry to delocalizeattractions, the result is elevated viscosity for a given amount ofsolids present in the composition. Higher viscosity would requiregreater addition of water to achieve printing viscosity, and loss ofpigment percentage (i.e. low applied color strength). In the specificexample of the biochar black pigment (as opposed to ancient sourcecarbon black), greater hydrogen bonding character is present as residualoxygen structures from cellulose. This is attenuated with resin choices(e.g. rosin citrate) having one pole of the structure with little/nohydrogen bonding structure. This geometry localizes the pigmentattractions (i.e. to the one pole that has more hydrogen bonding).

Formulating for optimal ink rheology is an effort to minimize wetattractions without eliminating those same attractions in a dry printedink. Biochar pigment must be combined with agents that lower hydrogenbonding, produce greater flow, greater applied solids, and lowerviscosity. One such agent to isolate and render less attractive theexcess oxygen content of biochar is a 100% BRC rosin adduct, as used inthe present invention.

Examples of rosin adduct materials include, but are not limited to,Filtrez rosin fumarates from Lawter, Reactol rosin-based polyester fromLawter, and Amberyl rosin maleates from Polimeros Sinteticos.

In preferred embodiments, the rosin adduct used in the present inventionis an anionic modified rosin resin ester. Preparation of the rosinadduct is described in WO 2021/231829. Colophony, consisting of rosinmonomer and dimer acids, is initially reacted with a material of thegeneral structure called alpha hydroxy carboxylic acids. Examples ofalpha hydroxy carboxylic acids include, but are not limited to, malicacid, fumaric acid, lactic acid, tartaric acid, ascorbic acid, citricacid, glycolic acid, hydroxycaproic acid, hydroxycaprylic acid, mandelicacid, phytic acid, and combinations thereof. This initial reactionproduces a rosin ester. A second reaction with any number of polyols canyield a higher molecular weight modified rosin ester. Rosin may also bepolymerized with any number of unsaturated compounds using a freeradical propagation method. A particularly preferred material is a 100%BRC rosin-citrate ester resin. The rosin adduct material is preferablymodified with lactic acid.

These 420 to 920 molecular weight modified rosins exhibit one pole ofzero hydrogen bonding sites, and another pole with hydrogen bondingsites that cannot interact with more than on biochar particle,eliminating delocalization of attractive forces and elevation ofviscosity. In other words, a long string of attractions requires moreenergy to move than a short and localized point of attraction. Some ofexamples of rosin-citrate ester resin structures are shown below (fromWO 2021/231829).

Rosin-citrate ester resins Structure Name and molecular weight

2-(3-((7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carbonyl)oxy)-2,5-dioxotetrahydrofuran-3-yl)aceticacid [M-H]⁻ = 457.2231

2-(((3-carboxy-2,5-dioxotetrahydrofuran-3-yl)oxy)carbonyl)-2-((7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carbonyl)oxy)succinicacid [M-H]⁻ = 587.2498

3,3′-((7,8-diisopropyl-1,4a, 10b,14-tetramethyl-1,2,3,4,4a,4b,5,6,7,8,9,10,10a,10b,11,12,13,14,14a,15,15a,15b,16,16a-tetracosahydrodibenzo[fg,ij]pentaphene-1,14-dicarbonyl)bis(oxy))bis(2,5-dioxotetrahydrofuran-3-carboxylicacid) [M-H]⁻ = 915.4583

Biochar pigment is available commercially, and comes in a range ofparticle size options. Biochar pigment is dissimilar from ancient carbonblack pigment in its high resilience to mechanical disintegration.Biochar tends to absorb mechanical energy without crushing to smalleraverage particle size, the result being a flexing of the structure,instead of sheering away structure. Use of black pigment in printinginks requires particle size to be reduced to about less than or equal to1 µm, to optimize the light absorbance efficiency. Established particlereduction techniques exist, known in the ink industry as milling. Onecommon established process for reducing (fracture resistant) particlesis a premix step with chemistries that chemically penetrate intomicro-fissures. Much like the expansion of a crack in glass, where waterpenetrates, freezes, and expands, surfactant chemistries have beencommonly utilized in the ink industry to chemically penetrate difficultgrind pigments, enhancing the mechanical reduction process. It should benoted that the biochar suppliers have additional mechanical techniquesand equipment to reduce particle size.

A key attribute of the invention is attainment of a non-pigment solidsnear 30% at a print viscosity near 28 seconds on a #2 EZ Zhan cupviscometer. There is a complex relation of both solids and viscosity tosuccessful delivery of ink to substrate. Resin solids are the majorfactor delivering physical performance of a printed ink. Pigment solids(biochar) is the major factor delivering color strength. It is paramountthat resin and pigment combinations do not interact to a point of highviscosity and low solids. The present inventive formulations show a lowviscosity, high solids compatibility of rosin-citrate ester resin withbiochar.

Robust mechanical rub resistance in a printed ink is a combination ofsurface hardness (determined with a pencil hardness test in the presentinvention) and flexibility. Optimal flexibility is attained when theglass transition temperature (Tg) of the ink or coating is less than 25°C., so that a film is formed at about room temperature. Most packaginghas a typical packaging usage near room temperature, i.e. about 22° C.to about 30° C. When the Tg is lower than room temperature, the polymersand additives will show elasticity and toughness at 25° C. A resin witha Tg that is lower than the packaging use temperature is a film former.If the Tg is higher, e.g. about 50° C., and the package is beingmechanically stressed at 30° C., the ink will likelycrack/shatter/powder. Conversely, if the Tg is far below the package usetemperature, the ink will be more prone to smear and transfer, that whenthe Tg is close to the usage temperature. This situation can bedescribed as “sticky.” Surface hardness is always a mechanical benefitat higher levels, where film formation is present. Historically,flexible packing with a pencil hardness greater than 2H and filmformation will display robust mechanical resistance.

Block resistance of a printed substrate is the prevention of transfer ofthe ink to the non-printed side of the substrate when the substrate isrolled. Persons skilled in the art use laboratory block testingequipment that produces 50 psi, 120° F. (~ 49° C.) and 66% relativehumidity for a duration greater than 72 hours, simulating printedmaterial transit in a hot truck. The printed sample is rolled up,producing a face-to-back configuration, before being loaded into blocktesting equipment.

Heat resistance is a requirement of many packaging applications, due touse of heated forming equipment. A common duplication of kinetic heatresistance is use of a heated sled (400° F., or ~ 204° C.) incombination with a Sutherland Rub Tester. A second static heatresistance test utilizes a Sentinel Heat Sealer, where the printedsample is placed between aluminum foil. The foil is subjected to 400° F.and 80 psi, evaluating transfer of ink to foil. The benefit of attainingand confirming heat resistance is prohibiting the transfer and build-upof printed ink on hot forming equipment.

There are additional (specific) performance requirements for uniquepackaging applications. The fast food industry, for example, places highimportance on sustainability and BRC elevation in their packaging. Fastfood uses sandwich wraps, carry out bags, folding cartons, polyethylene(PE) cups, and pre-print corrugated packaging. For those applications,the ink must resist soft drink solubility (simulated with a water wettednapkin rub), condiment contact without moving ink, and lack of inktransfer within a stack of nested containers. The ultimate proof of afunctional 100% BRC black ink is attaining all required propertiessimultaneously.

There are several finished ink examples shown in this application thatperform well for many common application requirements, using a unique100% BRC varnish as a grind/mixing vehicle, or as a coating whereapplicable/required.

In one embodiment, the present invention provides a water-based varnishcomposition, which can be used as a coating (i.e. as is, and referred toas a coating or a varnish), a pigment grind vehicle, or a mixing vehiclefor ink compositions (as referred to in the examples) - use of any ofthese terms refers to the water-based varnish. The varnish/grindvehicle/mixing vehicle comprises a rosin adduct and water. In someembodiments, the varnish/grind vehicle/mixing vehicle further comprisesone or more of L-lactic acid, ammonia, wax, a silicone compound, or achelating agent.

The varnish/grind vehicle/mixing vehicle typically comprises about 10wt% to about 30 wt% water, based on the total weight of the varnish. Forexample, the varnish/grind vehicle/mixing vehicle may comprise about 10wt% to about 25 wt% water, based on the total weight of thevarnish/grind vehicle/mixing vehicle; or about 10 wt% to about 20 wt%;or about 10 wt% to about 15 wt%; or about 15 wt% to about 30 wt%; orabout 15 wt% to about 25 wt%; or about 15 wt% to about 20 wt%; or about20 wt% to about 30 wt%; or about 20 wt% to about 25 wt%; or about 25 wt%to about 30 wt%.

The varnish/grind vehicle/mixing vehicle typically comprises about 10wt% to about 30 wt% rosin adduct, based on the total weight of thevarnish. For example the varnish/grind vehicle/mixing vehicle maycomprise about 10 wt% to about 25 wt% rosin adduct, based on the totalweight of the varnish/grind vehicle/mixing vehicle; or about 10 wt% toabout 20 wt%; or about 10 wt% to about 15 wt%; or about 15 wt% to about30 wt%; or about 15 wt% to about 25 wt%; or about 15 wt% to about 20wt%; or about 20 wt% to about 30 wt%; or about 20 wt% to about 25 wt%;or about 25 wt% to about 30 wt%.

When present, the varnish/grind vehicle/mixing vehicle typicallycomprises about 5 wt% to 15 wt% of an L-lactic acid composition. Forexample, the varnish/grind vehicle/mixing vehicle may comprise about 5wt% to about 10 wt% of an L-lactic acid composition, based on the totalweight of the varnish/grind vehicle/mixing vehicle; or about 10 wt% toabout 15 wt%. The L-lactic acid composition is typically provided as adispersion/solution in water, comprising about 88 wt% L-lactic acid, andabout 22 wt% water.

When present, the varnish/grind vehicle/mixing vehicle typicallycomprises about 10 wt% to about 30 wt% ammonia composition, based on thetotal weight of the varnish/grind vehicle/mixing vehicle. For examplethe varnish/grind vehicle/mixing vehicle may comprise about 10 wt% toabout 25 wt% ammonia composition, based on the total weight of thevarnish/grind vehicle/mixing vehicle; or about 10 wt% to about 20 wt%;or about 10 wt% to about 15 wt%; or about 15 wt% to about 30 wt%; orabout 15 wt% to about 25 wt%; or about 15 wt% to about 20 wt%; or about20 wt% to about 30 wt%; or about 20 wt% to about 25 wt%; or about 25 wt%to about 30 wt%. The ammonia composition is typically provided as 14.5Baume ammonia.

Wax may be included in the varnish/grind vehicle/mixing vehicle as a waxsuspension, or as micronized wax. Preferably, the wax is a natural wax,containing 75% to 100% BRC. When present, a wax suspension is typicallypresent in an amount of about 1 wt% to 10 wt% wax suspension, based onthe total weight of the varnish/grind vehicle/mixing vehicle. Forexample, the varnish/grind vehicle/mixing vehicle may comprise about 1wt% to about 5 wt% wax suspension, based on the total weight of thevarnish/grind vehicle/mixing vehicle; or about 5 wt% to about 10 wt%.The wax suspension is typically provided as a suspension comprisingabout 25 wt% wax, and about 75 wt% water. When present, thevarnish/grind vehicle/mixing vehicle typically comprises micronized waxin an amount of about 1 wt% to about 5 wt%, based on the total weight ofthe varnish/grind vehicle/mixing vehicle. Suitable wax suspensionsinclude, but are not limited to, amide wax (e.g. ethylene bistearamide(EBS) wax), erucamide wax, polypropylene wax, paraffin wax, polyethylenewax, polytetrafluoroethylene wax, carnauba wax, soybean wax, andcombinations thereof.

When present, the varnish/grind vehicle/mixing vehicle typicallycomprises about 0.05 wt% to about 1 wt% silicone compound, based on thetotal weight of the varnish/grind vehicle/mixing vehicle. When present,the varnish/grind vehicle/mixing vehicle typically comprises about 0.5wt% to about 3 wt% chelating agent, based on the total weight of thevarnish/grind vehicle/mixing vehicle. In certain embodiments, thechelating agent is a zinc chelating agent.

In some embodiments, the present invention provides a black pigmentdispersion. The black pigment dispersion comprises the mixing vehicleand biochar. In some embodiments, the black pigment may further compriseadditional water and surfactant.

The black pigment dispersion typically comprises about 5 wt% to about 20wt% of the varnish/grind vehicle/mixing vehicle as described above,based on the total weight of the pigment dispersion. For example, thepigment dispersion may comprise about 5 wt% to about 15 wt%varnish/grind vehicle/mixing vehicle, based on the total weight of thepigment dispersion; or about 5 wt% to about 10 wt%; or about 10 wt% toabout 20 wt%; or about 10 wt% to about 15 wt%, or about 15 wt% to about20 wt%.

The black pigment dispersion typically comprises about 10 wt% to about40 wt% biochar, based on the total weight of the pigment dispersion. Forexample, the pigment dispersion may comprised about 10 wt% to about 35wt% biochar, based on the total weight of the pigment dispersion; orabout 10 wt% to about 30 wt%; or about 10 wt% to about 25 wt%; or about10 wt% to about 20 wt%; or about 10 wt% to about 15 wt%; or about 15 wt%to about 40 wt%; or about 15 wt% to about 35 wt%; or about 15 wt% toabout 30 wt%; or about 15 wt% to about 25 wt%; or about 15 wt% to about20 wt%; or about 20 wt% to about 40 wt%; or about 20 wt% to about 35wt%; or about 20 wt% to about 30 wt%; or about 20 wt% to about 25 wt%;or about 25 wt% to about 40 wt%; or about 25 wt% to about 35 wt%; orabout 25 wt% to about 30 wt%; or about 30 wt% to about 40 wt%; or about30 wt% to about 35 wt%; or about 35 wt% to about 40 wt%.

When present, the black pigment dispersion typically comprises about 1wt% to about 5 wt% surfactant, based on the total weight of the pigmentdispersion. For example, the black pigment dispersion may comprise about1 wt% to about 2 wt% surfactant, based on the total weight of thepigment dispersion.

Surfactants are employed to produce wetting and/or equal distributionsof dissimilar polarity chemistries. For the combination of biocharpigments within a finished water-based ink, surfactants can have up to afive-fold utility when properly chosen for their hydrophilic-lipophilic(HLP) balance structures. Utility of surfactants includes: 1) during themilling of the pigment to minimal size, surfactants will prevent the(very polar) biochar from re-agglomerating and/or creating greaterparticle separation; 2) allowing close (sheering) contact with the(relatively lower polarity) rosin-citrate ester resin during themanufacture of the color concentrate (dispersion); 3 maximizing theresin solids of a finished ink at a target viscosity; 4) allowing auniform thickness of wet ink to transfer to the intended substrate; and5) maintaining lateral uniformity of color during application tosubstrate. Surfactants will always have high and low polarity as part oftheir structure. A best use of surfactants (or no use) is a very complexdecision in building finished water-based ink for those skilled in theart.

When additional water is added to the pigment dispersion, it istypically added in an amount of about 10 wt% to about 50 wt%, based onthe total weight of the dispersion. For example, water may be added inan amount of about 10 wt% to about 40 wt%, based on the total weight ofthe dispersion; or about 10 wt% to about 30 wt%; or about 10 wt% toabout 20 wt%; or about 20 wt% to about 50 wt%; or about 20 wt% to about40 wt%; or about 20 wt% to about 30 wt%; or about 30 wt% to about 50wt%; or about 30 wt% to about 40 wt%; or about 40 wt% to about 50 wt%.

The compositions of the present invention can be applied to any suitablesubstrate. Preferred substrates include those used for flexiblepackaging. The substrates can subsequently be used to prepare articles,such as fast food wraps, cups, etc.

EXAMPLES

The present invention is further described by the following non-limitingexamples, which further illustrate the invention, and are not intendedto, nor should they be interpreted to, limit the scope of the invention.

Examples 1 and 2 Mixing Vehicles

An inventive mixing vehicle was prepared according to the formulation inTable 1.

TABLE 1 Example 1 - 100% BRC mixing vehicle Material wt% Water 27.11-Lactic acid 88.0% in water 10.2 Silicone Defoamer 0.1 Add while mixing100% BRC rosin-citrate ester resin 23.7 Mix High Speed 30 minutes UntilUniform with some particulates Add Ammonia Very Slowly While Mixing topH 6.50 (no Higher) 14.5 Baume Ammonia 11.3 Mixture will appeartacky/stringy Mix 30 Minutes @ pH =6.50 Add Rapidly While Mixing 14.5Baume Ammonia 17.1 Add While Mixing in Order Carnauba Wax Suspension 25%in water 6.2 BRC EBS Micronized Wax 2.0 Silicone COF Compound 0.3 Whenfully dissolved & pH>9.2, add while mixing Zinc (Inorganic) ChelatingAgent 2.0 Total 100

The final Example 1 mixing vehicle has a viscosity of 670 cps, asmeasured using a Brookfield DV-E Viscometer, with a 62 spindle, at 30rpm and pH = 9 at 25° C.

The major performance resin within Example 1 is a 100% BRC rosin-citrateester resin, with an acid value of 210 mg KOH/g. The Example 1 formulais a wet reaction occurring between lactic acid and the rosin-citrateester resin, at pH of 6.50. The reaction occurs before the ester isfully neutralized. The lactic acid is believed to create additionalester linkages in the rosin-citrate ester resin, lowering the acidvalue, elevating molecular weight, and lowering the glass transitiontemperature (Tg) creating a film forming resin at room temperature (25°C.), from the non-film forming rosin-citrate ester resin. Beforereaction with lactic acid the rosin citrate resin had a Tg greater than35° C., tested as described below, which is a liability for flexibility.After reacting with lactic acid, the final structure was determined bySun Chemical Eurolab to be a Diels-Alder addition reaction of lacticacid (alpha hydroxyl structure) onto the anhydride sites of the rosincitrate resin, with a Tg below 25° C., resulting in a mechanical benefitof greater flexibility.

Example 2 mixing vehicle is similar to Example 1 mixing vehicle, exceptthat the lactic acid was replaced with additional rosin-citrate esterresin. The formulation of Example 2 is shown in Table 2.

TABLE 2 Example 2 - 100% BRC mixing vehicle without lactic acid Material% Water 34.0 Silicone Defoamer 0.1 14.5 Baume Ammonia 21.4% ADD WHILEMIXING 100% BRC rosin-citrate ester resin 34.0 WHEN DISSOLVED ADD INORDER WHILE MIXING Carnauba Wax Suspension 25% in water 6.2 BRC EBSMicronized Wax 2.0 Silicone COF Compound 0.3 ADD WHILE MIXING Zinc(Inorganic) Chelating Agent 2.0 Total 100

The final Example 2 mixing vehicle has a viscosity of 85 cps, measuredusing a Brookfield DV-E Viscometer with a 62 spindle, and pH = 9.6 at25° C.

Example 1 mixing vehicle exhibits the required mechanical strength,whereas Example 2 mixing vehicle does not. Generally, mechanicalstrength is the product of surface hardness and flexibility. Surfacehardness can be measured using the pencil hardness test as describedbelow. Flexibility is assessed via Tg, where one of ordinary skill inthe art understands that values lower than 25° C. and greater than 15°C. contribute a mechanical benefit. A composition with a Tg greater than30° C. may have the drawback of brittleness. A Tg of less than 15° C.may have the drawback of no resistance to mechanical force, in the formof smearing. The Tg property works in conjunction with the pencilhardness. Mechanical strength is most often manifest in printing inks asa resistance to color mobility or scuff. As objects come into contactwith printed materials, it is disadvantageous for the dry ink to powder,and likely transfer to skin, clothes, etc. It is advantageous for dryinks to hold together, and flex with impartment of mechanical energy,with no production of shattered ink or ink powder. Example 2 ismechanically inferior to Example 1 due to a higher Tg (lessflexibility).

TABLE A Mechanical benefit of lactic acid modification of rosin-citrateester resin Example Vehicle Pencil Hardness Glass Transition TemperatureTg Example 1 3H <25° C. Forms Flexible Film at room Temperature Example2 3H >25° C. does not form a film, powders under mechanical stress

The chemical modification lowering Tg in Example 1 will ultimatelyproduce the ability to flex (not shatter) and mechanical toughness inthe finished ink.

Examples 3 to 5 Biochar Pigment Dispersions

Examples 3 to 5 are biochar color dispersions. The chemicalfunctionality and subsequent finished ink performance are describedbelow. All three biochar black dispersions utilize Example 1 mixingvehicle as part of the chemistry. Example 3 uses an anionic surfactantin combination with Example 1 100% BRC mixing vehicle. Example 4 uses anon-ionic surfactant in combination with Example. Example 5 omitssurfactant entirely. The formulations of Examples 3 to 5 are shown inTables 3 to 5, respectively.

TABLE 3 Example 3 - 100% BRC black dispersion R4234-81E Material wt%Example 1 100% BRC Mixing Vehicle 16.2 lignin based polyelectrolyte(Anionic Surfactant) 3.8 Biochar 37.8 Water 42.2 Total 100

Example 3 black dispersion has a viscosity of greater than 45 seconds ona #2 EZ Zahn cup and pH = 9.0 at 25° C.

TABLE 4 Example 4 - 100% BRC black dispersion R4181-96A Material wt%Example 1 100% BRC Mixing Vehicle 18 Croda Brij L23 (nonionicSurfactant) 3.0 Biochar 37.8 Water 41.2 Total 100

Example 4 black dispersion has a viscosity of 42 seconds on a #2 EZ Zahncup and pH = 9.5 at 25° C.

TABLE 5 Example 5 - 100% BRC black dispersion 120220-1 Material wt%Example 1 100% BRC Mixing Vehicle 17.3 Biochar 37.8 Water 44.9 Total 100

The Example 5 dispersion flows for a short while after blade energy isintroduced (60 seconds), then becomes a non-pourable solid. This isknown as “setting up.” The solid must be stirred to pour. However,finished inks using this color dispersion, described do not set up (i.e.remain pourable). Example 5 has a pH = 9.3.

Examples 6 to 8 Finished Inks Using Black Dispersions of Examples 3 to 5

Examples 6 to 8 are finished inks containing the black dispersions ofExamples 3 to 5. The formulations of Examples 6 to 8 are shown in Tables6 to 8, respectively.

TABLE 6 Example 6 - 100% BRC black finished ink Material wt% Example 3Black Dispersion 65 Example 1 100 BRC Mixing Vehicle 35 Total 100

Example 6 finished ink has a viscosity of 31 seconds on a #2 EZ Zahn cupand a pH = 9.4 at 25° C.

TABLE 7 Example 7 - 100% BRC biochar black finished ink R4181-96BMaterial wt% Example 4 Black Dispersion 65 Example 1 100% BRC MixingVehicle 35 Total 100

Example 7 finished ink has a viscosity of 35 seconds on a #2 EZ Zahn cupand a pH = 9.1 at 25° C.

TABLE 8 Example 8 - 100% BRC biochar black finished ink R4181-96GMaterial wt% Example 5 Black Dispersion 65 Example 1 100% BRC MixingVehicle 35 Total 100

Example 8 finished ink has a viscosity of 40 seconds on a #2 EZ Zahncup, and a pH = 8.8 at 25° C.

Examples 9 and 10 Biochar Black Pigment Dispersions Based on Prior ArtChemistry

Examples 9 to 10 are additional biochar black pigment dispersions basedon Aquagreen chemistry. The formulations of Examples 9 and 10 are shownin Tables 9 and 10, respectively. Aquagreen is a commercial ink seriesfrom Sun Chemical which has been commercially printed/proven to befunctionally robust for the performance properties listed in Tables B,C, and D, for greater than 3 years. These are comparative in that,although having high BRC content, do not achieve 100% BRC content. Theinks prepared from the black dispersions of the present inventionexhibit properties as good as or better than the high BRC inks preparedfrom the black dispersions based on commercially available chemistry.Pigment dispersions and inks based on Aquagreen chemistry are theclosest prior art. Note that to achieve the required performanceproperties, the Aquagreen compositions contain high molecular weightresin emulsions. It is noteworthy that the inks of the present inventionachieve the required performance without the high molecular weight resinemulsions.

TABLE 9 Example 9 biochar black dispersion R4234-84A Material wt%Fumaric modified rosin 5.6 lignin based polyelectrolyte 3.8 Biochar 37.5Water 52.9 Defoamer and Biocide 0.2 Total 100

Example 9 pigment dispersion has a 47.1% total non-volatile content(%TNV), and 96.7% BRC.

TABLE 10 Example 10 black dispersion R4234-008C Material wt% ligninbased polyelectrolyte 8.8 Biochar 29.2 Water 61.8 Defoamer and Biocide0.2 Total 100

Example 11 Comparative Technical (mixing) Vehicle

Example 11 is a commercially available technical (mixing vehicle). It isGP37000030A Aquagreen Tech Vehicle available from Sun Chemical.

Examples 12 and 13 Comparative Black Finished Inks

Examples 12 and 13 are comparative black finished inks prepared usingExamples 9 and 10 black pigment dispersions, and Example 11 mixingvehicle. The formulations of Examples 12 and 13 are shown in Tables 11and 12.

TABLE 11 Example 12 comparative black finished ink Material wt% Example9 Black Dispersion 65 Example 11 Commercial vehicle 35 Total 100

Example 12 comparative finished ink has 45.2% TNV and 82.0% BRC.

TABLE 12 Example 13 comparative black finished ink Material wt% Example10 Black Dispersion 65 Example 11 Commercial vehicle 35 Total 100

Example 13 comparative finished ink has a 39.4% TNV and 81.5% BRC.

Example 14 Performance of Finished Inks

The following are qualifications for finished ink utility withinflexographic and rotogravure printed substrate applications.

Ambient Wet Stability / Initial Versus 1 Week Viscosity at RoomTemperature

A typical water-based printer will find best print performance in arange of viscosity from 18 seocnds to 35 seconds on a #2 EZ Zahn cupviscometer. Non-reduced inks should be formulated to an uncut viscositywithin that range. Ink samples are to be vigorously shaken by hand for10 seconds to assure uniformity. The test is documentation of initialviscosity using a #2 EZ Zhan cup viscometer, followed by documentationof viscosity after 7 days. A viscosity change (gain or loss) of morethan 5 seconds is unacceptable.

B. Heated Wet Stability / 24 Hour at 120° F. (~ 49° C.)

This test is identical to the ambient wet stability test, except thatwet samples are placed in a 120° F. oven for 24 hours before the secondviscosity reading. A viscosity change (gain or loss) of greater than 5seconds is unacceptable.

C. Color Strength / Applied Density at 25 Seconds Print Viscosity

Inks are reduced to 25 seconds on an #2 EZ Zahn cup using tap water,then applied to C1S bleached paperboard using a 200 line 7.0 BCM handproofer. Applied inks are dried in a 120° F. convection oven for 60seconds. An X-Rite 939 (set at Daylight 65, 10 degree observer) is usedto determine average density (V) of 3 readings. This is compared to astandard process density of V = 1.40 for determination of optimal aniloxselection or range. For rotogravure and flexographic applications, aselection of (cylinder or anilox) volume is typically from 1.2 BCM(billion cubic microns) to 15.0 BCM. Attaining an applied color densitywith a low BCM (called shallow) is much more difficult than using highBCM (deep) options. The 7.0 flexo anilox BCM is a common volume for lineartwork, and 2.0 BCM would be common to process artwork.

D. Static Heat Resistance / Sentinel Heat Sealer

The Sentinel heat sealer is set at 40 psi, 400° F., and 1 secondduration, using a top heated jaw. Ink is applied as in test C above. Theprint sample is aligned with the dull side of aluminum foil, theconstruction is inserted into the jaws of the heat sealer, and theclamping shoe is pressed. The constructions is allowed to cool to roomtemperature, and the foil is removed from the printed ink surface. Novisual transfer of ink to the foil is a passing result.

E. Kinetic Heat Resistance / Sutherland Rub Tester Heated Sled

This test is specific to the heated lamination process used in pre-printcorrugated substrates. Ink is applied on the substrate in a 7 inch long,2 inch wide strip (using the print method described in test C above).The substrate is affixed ink side up to the base of the equipment. Aheated sled is warmed to 400° F. The heated sled is pulled on thesurface of the print sample, passing from inked to non-ink areas. Thetest is set for 25 cycles. When complete, the substrate is inspected fortransfer of ink to the unprinted areas. Passing performance is novisible ink removal and no color movement to non-ink areas of thesubstrate.

F. Print Quality / Filament Inspection

Using a gloved (latex glove) hand, wet index finger with an amount ofink the size of a dime. Tap the wet index finger to the thumb in 5second increments until the ink is dry. Inspect the area between fingerand thumb while pulling apart. If a filament (looks like a cobweb)appears, it is an indication of a cohesion/adhesion imbalance in favorof cohesion. Filaments forming between ink plates and anilox or betweenthe gravure cylinder and stock leads to ink being deposited or throwninto non-print areas. A passing result is no visible filaments.

G. Print Quality / Glass Rewetting at pH = 9

Apply ink to a glass substrate, using the print method as in C above,allowing the ink to dry on the glass. This simulates the ink drying onthe anilox plate if the print run is stopped in the middle of the runfor any reason. Prepare a 100 g solution of tap water andmonoethanolamine (MEA) to pH = 9.0 (0.2% MEA required, depending on tapwater source). Holding the glass substrate with the dry ink facing up ata 45 degree angle, pipette 5 ml of the pH 9 solution, and slowly driponto printed area from 6 inches away. A passing result is full removalof ink from the glass in the drip area. That is, re-wetting of the inkon the glass plate, indicated by removal of the dry ink, is predictiveof re-wetting in the anilox-plate interface. If an ink cannot be re-wetthis would cause ink build up in the non-image areas, so that ink wouldbe delivered to areas where it should not be, also referred to as dirtyprint.

H. Print Quality / Gravure 5-minute Dry Then Rewet

Using a Geiger lab gravure press, load 100 grams of ink reduced to 20seconds #2 EZ Zahn cup into the pan. Turn on the press to 50% speed,with the blade engaged. Pull a test print as the inspection control.Stop the press rotation without releasing the blade. Allow the ink todry into the cylinder for 15 minutes under ambient conditions. Thisduplicates the potential power outages and effect on cell plugging.Start press rotation up after the 15 minutes. Allow the Geiger cylinderto rewet for 5 minutes. Pull another print. Inspect for evidence ofnon-uniform ink delivery. A passing result is when the printed imageremains uniform after re-wet, not showing a lower amount of ink deliveryin the areas of the etch that contained dry ink.

Block Resistance / Face to Back Ink Transfer

Prepare a 10 inch long by 3 inch wide strip of printed ink on 20# MGpaper (using a print method as described in C above). Roll the print upinto a cylinder on a finger. Fold the cylinder flat to a configurationof 1.5 inches by 3 inches. Set the block tester at 120° F., 50 psi, and66% relative humidity. Placed the flattened substrate cylinder into theblock tester, and leave for 24 hours. Upon removal from the blocktester, unwrap the sample, inspecting for any ink transfer from theprinted face to the unprinted back side of the stock. A passing resultis no visible ink transfer to the back side of the stock.

J. Mechanical Scuff / Sutherland Rub

Apply a finished ink with a viscosity of 29 seconds on a #2 EZ Zahn cupon the polyethylene (PE) side of polyethylene coated paper, using a 500line 4.0 BCM hand proofer, dry in a 120° F. convection oven for 30seconds, and then allow to cure in ambient conditions for greater than16 hours. This test is performed using a Sutherland rub tester with a 2#sled, and set for 25 cycles. The printed sheet is mounted to the 2# sled(ink side down so that the ink surface is exposed) facing an unprintedPE surface of the same stock, which is mounted onto the Sutherland base.The test consists of 25 cycles of rubbing. nk density was measured withan X-Rite 939 spectrophotometer using the setting D65 light /10 degreeobserver. A measurement taken from the non-test area (i.e. non-inktransfer) portion of the substrate density is subtracted from the (majorcontribution V, C, M, Y) measured density of the highest ink transferarea to determine ink transfer only. X-Rite transfer density must beless than 0.100 to pass established/historical print industry mechanicalrub requirements. Major color contribution is automatically determinedby many densitometers like X-Rite 939. It is the dominant reflectancewavelength of visible light in terms of Yellow (Y), Magenta (M), Cyan(C), and Black (V). An example of dominant absorbance is Magenta for apink, and Cyan for a dark forest green. Identifying the dominantabsorbance wavelength assures that the data includes the color with thehighest risk of observed transfer.

K. BRC / ASTM Method D6866

A sample of biochar pigment and Example 1 mixing vehicle were submittedto Beta Analytical, Miami, FL. Both samples attained a 100 BRC rating.The BRC content of the other materials used in the compositions of thepresent invention are available in a publically available samplingdatabase. The percent contribution of each material in a composition canbe calculated by multiplying the %BRC of the material by the wt% in thecomposition. Note that some items are generally recognized as 100% BRC,e.g. starch.

L. Microwave Safety

Finished ink is applied to 20# MG sandwich wrap stock, using theprinting method described in C above. A 4 inch by 2 inch printed sampleis placed in a 1200 Watt microwave oven, and a paper cup with 100 g ofwater is also placed in the microwave oven (to protect the microwaveemitter from burnout). The timer is set for 3 minutes on high setting.The test is stopped at any sign of smoke/spark/flame. If the 3 minutesis completed without incident, the printed sample is removed andinspected for discoloration or heat. A passing result is no evidence ofheat, discoloration, sparks, smoke, or flame.

M. Kinetic Water Resistance / Wet Napkin Test

This is a water wetted napkin quantitative mechanical rub transfer test.Ink is applied to 20# MG sandwich wrap stock, and cured (same method asabove). A fully water wetted napokin is pulled laterally oover a 4 inchrun of printed stock with a 2# Sutherland sled on top. A 3 inch by 4inch piece of copy paper is placed between the sled and the wettednapking to hold all the layers together during the test. The napkin isthen dried. The X-rite 939 density (major contribution V, C, M, Y) istaken for non-ink background, and the area of greatest ink transfer.Background density is subtracted from the ink transfer area, todetermine the ink only transfer density. Historical ink transfer densityvalues must be less than 0.050 to be acceptable by industry standards.

N. Specific Product Resistance - Condiment

This test evaluates ink transfer to a napkin with gentle hand wipe-awayof condiment over printed ink. The PE side of PE coated bleached stockis printed with the inks. The test employed the printed/cured PE side ofPE coated stock listed above. Each condiment (ketchup, mustard,mayonnaise, vegetable oil) is placed onto an ink area of printed stockin 1 inch (2.54 cm) diameter circles. After 15 seconds, a napkin is usedto remove the condiment. The napkin is inspected for ink transfer, andrated on a 1 to 5 scale: 1 = no visible ink transfer; 2 = barelyperceptible transfer of ink; 3 = slight transfer of ink; 4 = moderatetransfer of ink; 5 = excessive transfer of ink. A passing result showsslight to no ink transfer (1-3 rating) on the napkin.

O. Use of Overprint Varnish (OPV) - Requirements

In some embodiments, the mixing vehicle of the present invention can beused as a 100% BRC coating for applications requiring an overprintvarnish, or applications requiring additional resistance properties. Forapplications that are less than robust for water or mechanicalresistance, the mixing vehicle of the present invention is applied atgreater than 0.5#/ream dry application weight, using a 200 line, 7.0 BCMhandproofer over the printed area. The coated printed area is thenretested for the required properties. Many ink end-use applications haveresistance requirements that are very extreme, to a point whereoverprint varnishes are usually required. An example of one suchapplication that typically utilizes an overprint varnish would bepre-print clamshells or French fry scoops within the fast food packagingmarket. These packages have OPV on top of printed colors. There is noallowance of any ink transfer where food contact will occur. The Frenchfry scoops are shipped in a nested configuration (long tube one insidethe next), where the transfer of ink is never allowed.

Other applications, like cold cups, often have an option of OPV usedepending on many end use and processing factors.

P. Pencil Hardness Method

Wet prospective (i.e. to be tested) composition (which can be a singlepolymer, a vehicle, or a finished ink, as required) is applied to glassusing a 1.0 mil Byrd application over a distance of 8 inches. Thepolymer surface is dried with an air dryer for 30 seconds, or untilthoroughly dry to the touch. A control polymer with a known pencilhardness may also be applied in a different area of the glass (eachstrip should be labeled). The glass is placed over a white paper orsurface during test so that the carbon transfer (from the pencil) is notoverlooked. A 4B pencil is held comfortably and drawn back and forthover a 1 inch area on top of the test surface. Use very light pressurefor a first patch at a 30 degree angle, then use heavy pressure in asecond patch at an 80 degree angle (in the same area), but not so heavythat the pencil or graphite tip is broken.

Assess whether the carbon transfer is transferred to the print surface,and whether the surface is altered or destroyed. Assess whether you feela difference as the polymer is shattered by the pencil. Moving from softto hard pencils, the first pencil that does not transfer carbon orchange the surface of the print is the surface hardness of the resin(4B, 3B, 2B, FB, F, HB, H, 2H, 3H, 4H). When the pencil used is harderthan the test surface, the surface may shatter or powder, or the carbonwill not transfer. When the surface shatters or powders, it will beapparent on close inspection, and it can be “felt” on the pencil as adestructive vibration. Remember that flexibility is different fromsurface hardness. A shattered surface may allow carbon transfer. Thehistorical passing result for this test is hardness greater than orequal to 2H.

Q. Film Formation Method

This test is employed to determine whether a polymer will form a film ata desired temperature, such as room temperature (~ 25° C.). The polymeris applied to a glass surface and dried. The glass surface is heated toa desired temperature. A series of tests can be done at differenttemperatures, such as 25° C., 35° C., etc. A razor blade is used toremove the dried polymer from the glass surface. If the polymer comesaway in sheets, then the polymer forms a film at the temperature towhich the glass was heated. If the polymer powders, then the polymerdoes not form a film at that temperature. A passing result is filmformation at room temperature, with mechanical advantages describedearlier.

Results

Finished inks of the invention were tested in several of the performancetests listed above. The results are shown in Tables B, C, and D below.

TABLE B Dynamic application specifications Example Applied DensityX-Rite Filament Inspection Glass rewet Gravure Rewet Ex. 6 (AnionicSurfactant) 1.57 None Found Full ink removal from glass Observed No CellPlugging found Ex. 7 (Non-ionic Surfactant) 1.41 None Found Full inkremoval from glass Observed No Cell Plugging found Ex. 8 (No surfactant)1.52 None Found Full ink removal from glass Observed No Cell Pluggingfound

TABLE C Intrinsic static properties of finished black ink ExampleSentinel HR Microwave Safe? Block Resistance Ambient wet stability Ex. 6(Anionic Surfactant) No Ink Transfer to Foil Yes No Ink Transfer FoundAmbient viscosity gain = 3 sec 120° F. Viscosity gain =4 sec(Acceptable) Ex. 7 (Non-ionic Surfactant) Slight Ink transfer to foil(does not occur with Overprint protection) Yes No Ink Transfer FoundAmbient Viscosity gain = 2 sec 120° F. viscosity gain = 2 sec(Acceptable) Ex. 8 (No surfactant) No Ink Transfer to Foil Yes No InkTransfer Found No Ambient Viscosity gain 120F viscosity gain = 4 seconds(Acceptable)

Where “overprint” is indicated in Table D, this means that the finishedink was also tested after being overprinted with Example 1 mixingvehicle used as an overprint varnish.

TABLE D Intrinsic kinetic properties Example Sutherland HR SutherlandScuff Wet Napkin Condiment Ex. 6 (Anionic Surfactant) No ink movement tonon-Printed areas Density Transfer V=0.078 (Pass) Transfer Density V=0.054 (marginal). Slight ink transfer with ketchup & Mustard = 3; V=0.012 with Overprint (Pass) Mayo & Vegetable oil =1 (marginal); No inktransfer with Overprint - All condiments =1 (Pass) Ex. 7 (Non-ionicSurfactant) No ink movement to non-Printed areas Density TransferV=0.082 (Pass) Transfer Density V= 0.038 (Pass) No ink Transfer observedAll Condiments = 1 (Pass) Ex. 8 (No surfactant) No ink movement tonon-Printed areas Density Transfer V=0.154 (fail). Transfer Density V=0.038 (Pass) No ink Transfer observed All Condiments = 1 (Pass) Use ofOverprint V=0.009 (Pass)

Performance data shows that all three 100% BRC biochar black inksperform well for intrinsic and dynamic properties listed. Although notoptimal on their own in some of the intrinsic kinetic properties,Examples 6 and 8 could be recommended for applications using an overlacquer (i.e. overprint varnish). Examples of current fast foodpackaging applications that have an over lacquer include folding carton,pre-print corrugated board for clamshells, display materials (e.g. HappyMeals), and cold cups. Example 7 would be a best 100% BRC recommendationfor applications where no overprint varnish is available.Non-overprinted fast food applications include carry out bags, sandwichwraps, pinch bottom bags, and direct print clamshells.

The present invention has been described in detail, including thepreferred embodiments thereof. However, it will be appreciated thatthose skilled in the art, upon consideration of the present disclosure,may make modifications and/or improvements on this invention that fallwithin the scope and spirit of the invention.

1. A water-based liquid black ink composition comprising water, biocharpigment, and a rosin adduct, wherein the rosin adduct has 100%bio-renewable carbon (BRC) content.
 2. The ink composition of claim 1,comprising the components as a biochar pigment dispersion, and a mixingvehicle.
 3. The ink of claim 2, wherein the mixing vehicle comprises:(a) 10 wt% to 30 wt% water; and (b) 10 wt% to 30 wt% rosin adduct;wherein all amounts are based on the total weight of the mixing vehicle.4. The ink of claim 2, wherein the mixing vehicle further comprises oneor more of: (a) 5 wt% to 15 wt% L-lactic acid mixture; and/or (b) 10 wt%to 30 wt% ammonia; and/or (c) 1 wt% to 10 wt% wax suspension; and/or (d)1 wt% to 5 wt% micronized wax; and/or (e) 0.05 wt% to 1 wt% siliconecompound; and/or (f) 0.5 wt% to 3 wt% chelating agent; wherein allamounts are based on the total weight of the mixing vehicle.
 5. The inkcomposition of claim 2, wherein the biochar pigment dispersioncomprises: (a) 10 wt% to 40 wt% biochar; and (b) 5 wt% to 20 wt% of themixing vehicle; wherein all amounts are based on the total weight of thebiochar pigment dispersion.
 6. The ink composition of claim 2, whereinthe biochar pigment dispersion further comprises one or more of: (a) 1wt% to 5 wt% surfactant; and/or (b) 10 wt% to 50 wt% additional water;wherein all amounts are based on the total weight of the biochar pigmentdispersion.
 7. The ink composition of claim 1, wherein the rosin adductis a 100% BRC rosin adduct is a rosin ester, prepared by reacting one ormore rosin acid monomers and/or dimers with one or more alpha hydroxyacids.
 8. The ink composition of claim 7, wherein the alpha hydroxy acidis selected from the group consisting of malic acid, fumaric acid,lactic acid, tartaric acid, ascorbic acid, citric acid, glycolic acid,hydroxycaproic acid, hydroxycaprylic acid, mandelic acid, phytic acid,and combinations thereof.
 9. The ink composition of claim 7, wherein therosin ester is further reacted with one or more polyols to yield ahigher molecular weight modified rosin ester.
 10. The ink composition ofclaim 7, wherein the rosin is polymerized with an unsaturated compoundusing a free radical propagation method.
 11. The ink composition ofclaim 7, wherein the rosin adduct is 100% BRC rosin-citrate ester resin.12. The ink composition of claim 11, wherein the rosin-citrate esterresin is modified by further reacting the rosin-citrate ester resin withlactic acid.
 13. The ink composition of claim 4, wherein the waxsuspension comprises 25 wt% wax and 75 wt% water, based on the totalweight of the wax suspension.
 14. The ink composition of claim 4,wherein the wax is selected from the group consisting of amide wax,micronized wax, erucamide wax, polypropylene wax, paraffin wax,polyethylene wax, polytetrafluoroethylene wax, carnauba wax, soybeanwax, and combinations thereof.
 15. The ink composition of claim 14,wherein the micronized wax is ethylene bistearamide micronized wax. 16.The ink composition of claim 1, wherein equal to or greater than 80% ofthe carbon content is BRC.
 17. The ink composition of claim 1, whereinequal to or greater than 90% of the carbon content is BRC.
 18. The inkcomposition of claim 1, wherein 100% of the carbon content is BRC. 19.The ink composition of claim 1, comprising: (a) 30 wt% to 50 wt% mixingvehicle, based on the total weight of the ink composition, wherein themixing vehicle comprises: i. 10 wt% to 30 wt% water, based on the totalweight of the mixing vehicle; ii. 10 wt% to 30 wt% rosin adduct, basedon the total weight of the mixing vehicle; iii. 5 wt% to 15 wt% of anL-lactic acid mixture, based on the total weight of the mixing vehicle,wherein the L-lactic acid mixture comprises 88 wt% L-lactic acid and 22wt% water, based on the total weight of the L-lactic acid mixture; iv.10 wt% to 30 wt% of 14.5 Baume ammonia, based on the total weight of themixing vehicle; v. 1 wt% to 10 wt% wax suspension, based on the totalweight of the mixing vehicle, wherein the wax suspension comprises 25wt% wax and 75 wt% water, based on the total weight of the waxsuspension; vi. 1 wt% to 5 wt% micronized wax, based on the total of themixing vehicle; vii. 0.05 wt% to 1 wt% silicone compound, based on thetotal weight of the mixing vehicle; and viii. 0.5 wt% to 3 wt% zincchelating agent, based on the total weight of the mixing vehicle; and(b) 50 wt% to 70 wt% black dispersion, based on the total weight of theink composition, wherein the black dispersion comprises: i. 10 wt% to 40wt% biochar, based on the total weight of the black dispersion; ii. 1wt% to 5 wt% surfactant, based on the total weight of the blackdispersion; iii. 5 wt% to 20 wt% of the mixing vehicle of part (a),based on the total weight of the black dispersion; and iv. 10 wt% to 50wt% additional water, based on the total weight of the black dispersion;wherein 75% to 100% of the carbon content in the ink composition isbio-renewable carbon (BRC).
 20. A substrate comprising the inkcomposition of claim
 1. 21. An article comprising the substrate of claim20.